Solar Tiles

ABSTRACT

The invention consists of a solar thermal tile. The tile comprises a transparent portion for permitting the entry of sunlight into a heating space below the tile, and a chassis formed separately from the transparent portion on which the transparent portion is mounted. The chassis has at least one protrusion for forming an overlapping relationship with a neighbouring tile. The chassis may be formed from plastic or sheet metal. The transparent portion may be formed from a polycarbonate laminate.

FIELD OF THE INVENTION

The invention relates generally to the field of solar tiles. Theinvention more specifically relates to the provision of solar heating inbuildings using solar thermal tiles, and the provision of electricityusing solar photovoltaic tiles.

BACKGROUND OF THE INVENTION

The major source of power in the industrialized world is fossil fuelcombustion. The supply of fossil fuels is finite, and furthermore, theburning of fossil fuels is believed to contribute greatly toenvironmental pollution and global warming. Nuclear power is also usedfor electricity generation but nuclear power stations are potentiallyextremely dangerous if the reactors are not closely monitored, and thefission process generates highly dangerous waste. Consequently, a globalneed to develop new ways of generating power has been recognized.

Therefore, so-called ‘renewable energy sources’ have become the focus ofmuch attention. These renewable sources include wave, wind and solarpower. All of these sources of power are effectively infinite. In somecountries (such as the UK) the government provides financial incentivesto individuals and organizations that use alternative energy sources,further increasing interest in these technologies. Consumers who are‘environmentally aware’ welcome products and services that do notnegatively impact the environment.

Domestic and industrial water heating consumes a large amount of power.This is both expensive for the consumer, and, if that energy is derivedfrom fossil fuel combustion or nuclear fission, environmentallydamaging. Therefore, a means of water heating powered by a free,alternative energy source is highly desirable.

Solar energy is renewable and its generation causes no environmentaldamage. Even in non-tropical climes, solar energy is a significantsource of power; a south facing roof on a building in Britain receivesabout 1000 kWh/m² per year. Solar energy may be harnessed in solarthermal systems to heat water directly, or by using photovoltaic cellsto generate electricity.

Solar thermal systems typically use solar energy incident on buildingsurfaces to heat water. Existing solar thermal systems are oftendifficult to integrate with roofs, either during construction of theroof or as an addition to an existing roof. They may requiremodification to the supporting structure of the roof, or they may not becompatible with conventional roofing tiles. Conventional solar thermalsystems may be heavy, making them difficult, or even hazardous, toinstall on roofs. In some cases, cranes may be required to lift andposition solar thermal systems.

Some conventional solar thermal systems take the form of assemblies thatare fixed on top of an existing roof. A typical example is the MEGASUN™solar hot water heater, available from Helioakmi Ltd., Nea Zoi,Aspropyrgos, 19300, Attiki, Greece. The MEGASUN heater consists of awater storage tank and a solar energy collector on a support base. Waterfrom the tank is circulated through the solar energy collector, whichtransfers heat accumulated from the sun to the water. The support base,which is adjusted according to the angle of the roof, is screwed on topof the roof. The storage tank and collector are then assembled on thesupport base. Such specific installation procedures may necessitatespecial staff training and tools.

Other known solar thermal systems consist of solar thermal tiles thatare designed to replace conventional tiles in the roof. These tiles aretransparent to solar radiation. The solar radiation that passes throughthe tile heats a thermal collector in a space under the tile, within theroof. The tile described in International Patent Application WO-02/31415comprises a one piece transparent polycarbonate moulding. As the tilesare made of polycarbonate, they are susceptible to damage. They are alsodifferent in appearance to conventional tiles. Furthermore, it is oftendesirable to integrate solar thermal tiles with photovoltaic tiles inorder to produce both hot water and electricity from solar energy. Asolar thermal tile as described in International Patent ApplicationWO-02/31415 would have a very different appearance to a photovoltaictile incorporating a photovoltaic laminate. This causes aestheticproblems and results in a heterogenous overall appearance when thesetiles are incorporated into a building surface.

It is an object of the present invention to provide a solution to theabove problems.

According to the present invention there is provided a solar thermaltile, the tile comprising a transparent portion for permitting the entryof sunlight into a heating space below the tile, the tile furthercomprising a chassis, formed separately from the transparent portion, onwhich the transparent portion is mounted, wherein the chassis comprisesat least one protrusion on at least one edge, the protrusion forming anoverlapping relationship with a second tile when correctly mountedadjacent thereto. In the context of the present invention, a ‘chassis’is a support structure. Preferably, the chassis surrounds at least partof another component.

By providing a chassis, the transparent portion may be supported andprotected, facilitating ease of storage, handling and fitting.Furthermore, the chassis may fulfil an aesthetic function. A tile formedentirely of a transparent material, such as glass or polycarbonate,would be less durable in comparison to the present invention. A chassisprotects the transparent material, thereby allowing the tiles to bereadily stacked for storage and transport.

The protrusion facilitates a good fit between the tiles, helping tomaintain building accuracy, and further reinforces the whole roof. Byproviding a protrusion on the chassis, not the transparent material, thechassis bears any loads or impacts inflicted on the building surface,thus preserving the transparent material. In addition to forming anoverlapping relationship, the protrusion can be formed to interlock withthe neighbouring tile, further strengthening the overall strength of theset of fitted tiles in the building surface. Furthermore, theoverlapping relationship formed between a tile according to the presentinvention and a neighbouring tile helps ensure that the roof isweatherproof.

The chassis is preferably made of non-transparent material. By providinga chassis made of non-transparent material, materials that are strong,easily formed and lightweight may be employed. Such materials canprovide the support and protection necessary for the transparentportion. Thus, by combining a transparent portion and a non-transparentchassis, the necessity for a transparent portion for solar thermalheating is combined with the advantages of non-transparent materials interms of durability, ease of manufacture, and ease of integration withexisting conventional roofing tiles. The non-transparent material may bemetal. The metal may be folded to form the chassis, giving a highlydurable and readily manufactured chassis. Alternatively, thenon-transparent material may be a plastic, with the concomitantadvantage of non-corrosion.

The invention further contemplates providing a set of tiles,incorporating at least one solar thermal tile according to theinvention. A solar thermal tile according to the present invention isreadily integrated with conventional roofing tiles, and thus may beprovided as part of a set of tiles for installation in a buildingsurface. A building surface may be a roof or a wall.

The set of tiles preferably further comprises photovoltaic tilescomprising photovoltaic cells. The photovoltaic tiles may comprise achassis. The chassis confers similar advantages when provided incombination with a photovoltaic cell as it does when provided incombination with a transparent portion of a solar thermal tile. It wouldin some circumstances be desirable to integrate solar thermal waterheating tiles and photovoltaic tiles in the same building surface, inorder to heat water and generate electricity on those building surfacesthat receive the most incident sunlight. By providing a building surfaceincorporating a set of tiles comprising solar thermal tiles andphotovoltaic tiles according to an embodiment of the present invention,a durable and aesthetically uniform building surface that supplies solarthermal energy and solar electricity is obtained.

Further features and advantages of the invention will become apparentfrom the following description of preferred embodiments of theinvention, given by way of example only, which is made with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a solar thermal tile as an embodiment of the presentinvention.

FIGS. 2 a, 2 b, and 2 c illustrate right, left and front end views ofthe solar thermal tile illustrated in FIG. 1.

FIG. 3 illustrates the underside of the solar thermal tile illustratedin FIG. 1.

FIG. 4 illustrates an embodiment of the present invention, incorporatedinto a building surface.

FIG. 5 illustrates the embodiment of the invention of FIG. 1incorporated into a building surface.

FIG. 6 illustrates a photovoltaic tile.

FIG. 7 illustrates the underside of the photovoltaic tile of FIG. 6.

FIG. 8 illustrates an embodiment of the invention in combination with aphotovoltaic tile, in a building surface.

FIGS. 9 and 10 illustrate an embodiment of the invention incorporatedinto a building.

FIG. 11 illustrates an alternative embodiment of the invention, incombination with a conventional roofing tile.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a solar thermal tile 1 according to a firstembodiment of the invention. The transparent portion 2 consists of apolycarbonate sheet supported in the chassis 6. Alternatively, thetransparent portion may consist of toughened glass. The transparentportion may be affixed to the chassis using a sealant, and/or with tape,bolts, or screws. The chassis 6 is formed of folded sheet metal. Thechassis 6 comprises a supporting bar 3 (shown in FIG. 2), a rear overlapsection 8, a front end 10, and left and right ends 12 and 14,respectively. In an embodiment, the chassis 6 is formed in two parts,the first part consisting substantially of rear overlap section 8,supporting bar 3 and portions of the left end 12 and right end 14, thesecond part consisting of the rest of the chassis, comprising front end10, the remainder of left and right ends 12 and 14, and the portion ofthe chassis that surrounds transparent portion 2. It will be recognisedthat the chassis could, however, be formed in one unitary part, or itcould be made of several individual parts.

The left end 12 has a first protrusion 16 which both co-extendssubstantially with the left end 12 and protrudes horizontally outwardsfrom the left end 12. The right end 14 has a similar, second protrusion18. The first and second protrusions 16 and 18 form an overlappingrelationship with another adjacent tile placed alongside (along thehorizontal axis). The adjacent tile may be another solar thermal tileaccording to an embodiment of the invention, or a conventional roofingtile, or a photovoltaic tile, or another form of building surface.

In an embodiment, the chassis is formed of folded sheet metal. Thechassis may be formed from several individually formed folded sheetmetal sections, which are bonded together by welding and/or riveting.The chassis may be powder-coated, galvanised, painted, or plastic-coatedin order to prevent corrosion. In a specific embodiment, the chassis isformed from several sections of folded steel, TIG (tungsten inert gas)welded and pop-riveted together. The assembled chassis is powder coated.

FIG. 2 a shows the right end (profile) view of the solar thermal tile 1,showing right end 14. Second protrusion 18 can be seen coextending alongright end 14, and incorporates a downturned edge which forms anoverlapping relationship with a neighbouring tile.

FIG. 2 b shows the left end (profile) view of the solar thermal tile 1,showing left end 12. The first protrusion 16 extends from the left end12. First protrusion 16 incorporates an upturned edge, and forms anoverlapping relationship with a neighbouring tile. The formation of theprotrusion may be altered according to the form of a neighbouring tile.

In another embodiment, the protrusion may be formed so as to interlockwith a neighbouring tile. For example, the edges could be extended so asto make physical contact with a neighbouring tile.

FIG. 2 c shows the front view of the solar thermal tile 1. The front end10 and the supporting bar 3 can be seen. The first and secondprotrusions 16 and 18 can be seen extending horizontally from right andleft ends 12 and 14, respectively. When two solar thermal tiles 1 areplaced correctly adjacent with respect to one another, the firstprotrusion 16 of a first tile would form an overlapping relationshipwith the second protrusion 18 of a second tile. The overlappingrelationship of the first and second protrusions 16 and 18 forms arobust, accurate, space efficient and weatherproof interconnectionbetween the two tiles.

FIG. 3 shows a bottom view of the tile of FIGS. 1, 2 a, 2 b and 2 c.Right end 14 and front end 10 are indicated for the purposes oforientation. The underside of chassis 6 incorporates apertures 30, 31,32 and 33. The apertures transmit solar radiation that has passedthrough the transparent portion 2 (shown in FIG. 1) from the tile to theheating space below the tile.

FIG. 4 illustrates the incorporation of a tile into a building surfaceaccording to an embodiment of the invention. FIG. 4 shows a profile viewof solar thermal tile 1 incorporated into a roof, between conventionaltiles 20 and 22, the roof having an apex 24. The solar thermal tile 1 issupported on a first batten 34A by the supporting bar 3. The solarthermal tile 1 is further supported by overlapping with conventionaltile 22. The first and second battens 34A and 34B are horizontal woodenbattens, as found in many conventional roofs. The chassis 6 andsupporting bar 3 are provided with holes, in order to secure the tile tothe batten with screws or bolts.

Beneath solar thermal tile 1 is a heating space 35. The heating space 35is enclosed within container 39 to prevent convective heat loss.Container 39 is supported between battens 34A and 34B. The heating space35 includes a heating surface 36. The heating surface 36 is made up oftwo sheets of conductive material, such as a metal. The heating surfacemay be treated in a number of ways, in order to maximise its absorptionin the solar spectrum while minimising its heat emission characteristicsin the infra-red region of the spectrum. In this embodiment, heatingsurface 36 is painted black for maximum absorption. The heating surface36 is in conductive communication with a pipe 37, which contains water.The pipe 37 is made of a thermally conductive material, such as copper.Container 39 comprises a layer of insulation 38. The container 39 isideally airtight, in order to prevent loss of heat by convention, and tomaintain a heated air environment around the heating surface 36 and thepipe 37.

In this embodiment of the invention, sunlight passes through transparentportion 2 of solar thermal tile 1, then through apertures 30, 31, 32 and33 (shown in FIG. 3), to heating space 35. In heating space 35, thesunlight is absorbed by heating surface 36. Heating surface 36 conductsheat energy to pipe 37, where the heat energy is absorbed by the waterwithin the pipe. The heated water is then pumped away actively orpassively, for domestic use. Insulating layer 38 ensures that thetemperature of heating space 35 is maximised by preventing loss of heatenergy. Loss of heat energy by convection is further minimised by theinsulative blanket of still air around heating surface 36 and pipe 37.The transparent portion 2 may be double glazed (i.e. include more thanone transparent sheet), to further reduce heat loss.

The rear overlap section 8 of the chassis of solar thermal tile 1 isformed to accommodate another tile in the vertical axis. When solarthermal tile 1 is incorporated into a building surface such as a roof,tiles placed above solar thermal tile 1 overlay the rear overlap section8. The conventional roofing tile 20 overlaps the solar thermal tile 1 atthe rear overlap section 8, while the solar thermal tile 1 itselfoverlaps conventional roofing tile 22. Rain will flow away from the roofapex 24 down the tiles, and due to the arrangement of the overlapping ofthe conventional tile 20, solar thermal tile 1 and conventional tile 22,will be prevented from leaking through the roof.

FIG. 5 illustrates solar thermal tile 1 integrated into a buildingsurface 60. Dashed lines indicate features that would not be visible,such as protrusions or the edges of tiles that are concealed by otheroverlapping tiles. Solar thermal tile 1 is shown to scale with thebuilding surface 60, which consists of three horizontal rows ofoverlapping tiles.

The building surface 60 may form part of a roof, or a wall. The buildingsurface 60 includes conventional tiles 50-59 and solar thermal tile 1.Dashed lines indicate features that are, in practice, hidden from viewbehind other features. Protrusions 16 and 18 form overlappingrelationships with cooperating formations on neighbouring conventionaltiles 54 and 55 at edges 62 and 64. It can be seen that, in the verticalaxis, the edges of conventional tiles 50-53 overlap solar thermal tile1, and solar thermal tile 1 overlaps part of conventional tiles 56, 57,58 and 59, in order to create a waterproof, sloping building surface ofuniform appearance. Solar thermal tile 1 is equivalent in width to fourconventional tiles, and in length is equivalent to one conventionaltile, in order to fit into the building surface without the need forspecially sized surrounding tiles.

FIG. 6 shows a photovoltaic tile 90 according to an embodiment of theinvention. Photovoltaic tile 90 incorporates a chassis 92, aphotovoltaic laminate 94, and protrusions 96 and 98. The photovoltaiclaminate 94 is made up of a protective layers and photovoltaic cells(not shown) and generates electricity from incident solar light. Thetile may also include a rectifier (not shown) to convert the directcurrent output of the photovoltaic cells to alternating current.

The chassis 92 is formed of folded sheet metal and includes a front end91 and a rear overlay section 95. In this embodiment of the invention,chassis 92 is similar in appearance and construction to chassis 6 ofFIG. 1. In this way, a homogenous and uniform appearance will beachieved when photovoltaic tile 90 and solar thermal tile 1 areincorporated into the same building surface. The provision of a chassisconfers similar advantages for a photovoltaic tile as for a solarthermal tile, such as lightness, durability, mechanical strength, easeof handling and fitment, ease of manufacture, and ease of integrationwith existing conventional roofing tiles. Note, however, that front end91 includes ventilation holes, to allow airflow into the tile andprevent overheating of the photovoltaic cells within the tile. Theventilation holes are not present in the solar thermal tile chassis.

FIG. 7 shows the underside of photovoltaic tile 90, showing apertures110, 111, 112, and 113. Front end 91 is shown for the purposes oforientation. Photovoltaic cells within chassis 92 are connected to poweroutlet 115. Power outlet 115 is connected to power lines 116 and 118.Power lines 116 and 118 end in plugs 120 and 122, respectively. Plugs120 and 122 may be connected to an electrical network, in order tosupply electricity to the network, or to a neighbouring photovoltaiccell, in order to provide an array of photovoltaic tiles, the arraybeing connected as a whole to an electrical network.

FIG. 8 shows an embodiment of the invention in combination withphotovoltaic tile 90. Building surface 70 comprises three horizontalrows of tiles and incorporates a solar thermal tile 1 according to anembodiment of the present invention, and the photovoltaic tile 90. As inFIG. 5, dashed lines indicate features that would not be visible inpractice, such as the edges of tiles and protrusions that are underneathother tiles. The first and second protrusions 16 and 18 of solar thermaltile 1 form overlapping relationships with neighbouring conventionaltiles 101 and 102 respectively. Protrusions 96 and 98 of photovoltaictile 90 form overlapping relationships with neighbouring conventionaltiles 103 and 104. It can be seen that solar thermal tile 1 andphotovoltaic tile 90 are overlapped by conventional building tiles abovethem, and solar thermal tile 1 and photovoltaic tile 90 themselvesoverlap a layer of conventional tiles below them. Building surface 70provides both solar thermal water heating and solar-generatedelectricity, which is desirable to ‘environmentally-aware’ consumers.

FIG. 9 shows an embodiment of the invention, incorporated into a surfaceof a building. Building 140 has a roof 142, the roof includingconventional tiles in area 144, an area of solar thermal tiles 200comprising solar thermal tiles according to an embodiment of the presentinvention, and an area of photovoltaic tiles 202 comprising photovoltaictiles according to the present invention. Building 140 has a plumbingsystem (shown in FIG. 10) that allows the solar thermal system to addheat to the domestic hot water system in the building.

With respect to the placing of the area of solar thermal tiles 200 andthe area of photovoltaic tiles 202 on building 140, non-tracking(stationary) solar thermal and photovoltaic systems on buildings in thenorthern hemisphere should be placed on a surface that faces true south.The systems should be placed at an angle equal to the latitude of thegeographical area of the building, in order to ensure maximum incidentsunlight. The surface should not be shaded. The building may include abattery system (not shown) to store the electricity produced byphotovoltaic tiles.

FIG. 10 shows part of the plumbing system of building 140 shown in FIG.9. FIG. 10 illustrates a portion of the inside surface of the roof 142where the area of solar thermal tiles 200 and the area of photovoltaictiles 202 meet. The roof 142 is of a known type, consisting of a timberframework overlaid with tiles, and incorporates vertical joists 150 andhorizontal battens 160 on which all tiles are placed and to which alltiles are secured.

Solar thermal tile 146 according to an embodiment of the invention andphotovoltaic tile 148 according to an embodiment of the invention areshown. Solar thermal tile 146 and photovoltaic tile 148 are secured tothe batten 162 by supporting bars 152 and 154, respectively.Photovoltaic tile 148 includes apertures 156, 157 and 158, andelectricity generated by the photovoltaic cells within the photovoltaictile 148 is provided to an electrical network via electrical cable 164.Solar thermal tile 146 has a heating space 166. In an embodiment of theinvention the heating space 166 is arranged similarly to the heatingspace 35, as shown in FIG. 4. Cold water is pumped into heating space166 via inlet pipe 168 and out via outlet pipe 170. In this way, theplumbing system of the building is connected to the fluid heating systemof the tile.

FIG. 11 illustrates an alternative embodiment of the invention, incombination with a conventional tile. The ‘Galloway’ tile (availablefrom Russell Roof Tiles, Wellington Road, Burton-on-Trent, Staffs DE142AW, UK) is an example of a conventional tile. A cross section is shown.A solar thermal tile 180 according to an embodiment of the invention hasa protrusion 182. The conventional tile 186 has a corrugated edge 188.It can be seen that, in addition to forming an overlapping relationshipin accordance with the invention, the protrusion 182 and corrugatededges 188 of the protrusions can form a firm, robust interlock.Alteration of the dimensions of the protrusion 182 and corrugated edge188 will allow physical contact, further strengthening theinterconnection between solar thermal tile 180 and conventional tile186.

It will be understood that various modifications may be made to theinvention. In an embodiment of the invention, the heating space maycontain a heat collecting assembly. In an embodiment, this assembly maytake the form of an array of tubes containing a heating medium. Thetubes of the assembly may be formed of a metal such as copper, which ischeaply and freely available, easily worked into complex tubular shapes,and is highly conductive.

The heating medium may be a liquid such as water, which may be useddirectly for domestic hot water applications, or oil, in which case theheat would need to be transferred from the oil to water.

The shape of the protrusion may be altered. For example, the protrusionmay be corrugated to match the corrugation of a neighbouringconventional roof tile.

In an embodiment where the heat collecting assembly contains a liquidheating medium, the assembly is arranged to be in fluid communicationwith the outside of the tile, so that heating medium may be pumped inand out of the tile. In an alternative embodiment of the invention, theheat collecting assembly may take the form of a grid made up of solidmetal wire, in conductive communication with the outside of the tile.The space occupied by the heating assembly may be lined with areflective material, such as metal foil, in order to reflect radiationfrom the heat collecting assembly back towards it. Alternatively,thermal insulation such as rock wool or fibreglass may be used in theheating space.

Due to the temperature difference between the heating space and the airoutside the building surface, condensation may form in the heatingspace. The chassis may incorporate air holes to prevent the accumulationof moisture within the tile.

A tile according to the present invention may be used in a wide varietyof climates and may be adapted for differing environments. For example,in coastal regions the chassis may be made of anodised aluminium, toprevent corrosion caused by humidity and salt water. The chassis may bemade with an inwardly reflective coating, in order to prevent any heatloss from the heating space.

The transparent portion may be a sheet made of polycarbonate, oralternative materials such as laminated glass. Glass and steel havesimilar thermal expansion characteristics. An advantage of such acombination is that, in high temperatures, the structure of the tile asa whole will not be compromised as the transparent portion and thechassis will expand at approximately the same rate.

An embodiment of the invention may be implemented in a variety oflocations. An embodiment of the invention may be implemented in bothpermanent and temporary buildings, during or after construction.

1-20. (canceled)
 21. A set of tiles, incorporating at least oneconventional roof tile, at least one solar thermal tile and at least onephotovoltaic tile, wherein the at least one solar thermal tile comprisesa chassis on which is mounted a transparent portion for permitting theentry of sunlight into a heating space below the at least one solarthermal tile, the chassis being formed separately from said transparentportion, wherein the chassis comprises at least one protrusion on atleast one edge and at least one aperture, said transparent portion beinglocated to cover the at least one aperture, said protrusion beingadapted to form an overlapping relationship with a second tile whencorrectly mounted adjacent thereto, wherein the at least one solarthermal tile has a tile width which is a multiple of the width of the atleast one conventional roof tile, and wherein the at least onephotovoltaic tile comprises a photovoltaic cell, a chassis which issubstantially identical in external appearance to that of the at leastone solar thermal tile and a photovoltaic laminate, said photovoltaiclaminate being mounted in substantially the same position on thephotovoltaic tile chassis as the transparent portion on the solarthermal tile chassis.
 22. The set of tiles of claim 21, wherein thechasses comprise a non-transparent material.
 23. The set of tiles ofclaim 22, wherein the non-transparent material is a plastic.
 24. The setof tiles of claims 22, wherein the chasses are moulded components. 25.The set of tiles of claim 22, wherein the non-transparent material is ametal.
 26. The set of tiles of claim 25, wherein the chasses comprisefolded sheet metal.
 27. The set of tiles of claim 21, wherein thetransparent portion has peripheral edges, and the solar thermal tilechassis is arranged to support the transparent portion at saidperipheral edges.
 28. The set of tiles of claim 21, wherein thetransparent portion comprises sheet material.
 29. The set of tiles ofclaim 21, wherein the transparent portion is formed from polycarbonatematerial.
 30. The set of tiles of claim 21, each chassis furtherincorporating a rear overlap surface, the rear overlap surface beingformed to support a third tile placed above the at least one solarthermal tile and/or the at least one photovoltaic tile.
 31. The set oftiles of claim 21, wherein the chassis of the photovoltaic tile furthercomprises at least one hole to allow airflow.
 32. The set of tiles ofclaim 21, wherein said multiple is four.
 33. A building comprising asurface, the surface comprising a set of tiles according to claim 21,the building further comprising a fluid heating system mounted in aheating space behind one or more solar thermal tiles.